Question 995952
Convert minutes to hours:
{{{ 24/60 = .4 }}} hrs
{{{ 36/60 = .6 }}} hrs
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Let {{{ s }}} = the speed of the hummingbird in still air
{{{ s + 6 }}} = bird's speed flying with the wind
{{{ s - 6 }}} = bird's speed flying against the wind
Let {{{ d }}} = the one-way distance the bird flies
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Equation for flying with the wind:
(1) {{{ d = ( s+6 )*.4 }}}
Equation for flying against the wind:
(2) {{{ d = ( s-6 )*.6 }}}
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Substitute (1) into (2)
{{{ ( s+6 )*.4 = ( s-6 )*.6 }}}
{{{ .4s + 2.4 = .6s - 3.6 }}}
{{{ .2s = 6 }}}
{{{ s = 30 }}}
The speed of the hummingbird in still air is 30 mi/hr
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check:
(1) {{{ d = ( s+6 )*.4 }}}
(1) {{{ d = (30+6 )*.4 }}}
(1) {{{ d = 36*.4 }}}
(1) {{{ d = 14.4 }}}
and
(2) {{{ d = ( s-6 )*.6 }}}
(2) {{{ d = ( 30-6 )*.6 }}}
(2) {{{ d = 24*.6 }}}
(2) {{{ d = 14.4 }}}
OK